Ng liquid metal particles in an aqueous medium method of forming and dispersing a plurality of discrete non coalesci

ABSTRACT

A METHOD OF FORMING AND DISPERSING A PLURALITY OF DISCRETE, NON-COALESCING LIQUID METAL PARTICLES IN AN AQUEOUS MEDIUM IS DISCLOSED. AT LEAST ONE LIQUID METAL SOURCE IS COMBINED WITH A STABLE AQUEOUS COLLOIDAL SOLUTION, FORMED BY A CONTROLLED HYDROLYSIS AND NUCLEATION REACTION AND COMPRISING INSOLUBLE HYDROUS OXIDE PARTICLES OF ONE OR MORE SELECTED ELEMENTS, SUCH SOLUTIONS BEING EXEMPLIFIED IN APPLICATION SER. NO. 8,022, FILED FEB. 2, 1970, NOW U.S. PAT. NO. 3,657,003. THE COMBINED SOURCE AND COLLOIDAL SOLUTION ARE THEN SUBJECTED TO A DISPERSIVE FORCE TO (1) FRACTIONATE THE METAL SOURCE TO FORM THE PLURALITY OF LIQUID METAL PARTICLES, AND (2) DISPERSE THE NON-COALESCING PARTICLES WITH THE COLLOIDAL SOLUTION. WHERE THE LIQUID METAL SOURCE IS INITIALLY FRACTIONATED IN A SUITABLE MANNER, THE DISPERSIVE FORCE THEN MERELY DISPERSES THE NON-COALESCING PARTICLES.

Sept. l1, 1973 .T. KENNEY ETAL 3,7585414 METHOD OF FO NG AND DISPERSING A PLURALITY OF DISCRETE, NONCO .SC. LIQUID METAL PARTICLES IN AQU US MEDIUM Filed Aug. 19, 1971 2 Sheets-Sheet l L/VENTURE' J. T. KENNEY ET AL 3,758,414 METHOD OF FORMING AND DISPERSING A PLURA I Y OF DISCR NON-CO J SCING LIQUID MET PA CLES 1N AQUEOUS MEDIUM 2 Sheets-Sheet L:

Filed Aug. 19, 1971 Sept. 11, 1973 United States Patent O U.S. Cl. 252-313 R 5- Claims ABSTRACT OF THE DISCLOSURE A method of forming and dispersing a plurality of dis* crete, non-coalescing liquid metal particles in an aqueous medium is disclosed. At least one liquid metal source is combined with a stable aqueous colloidal solution, formed by a controlled hydrolysis and nucleation reaction and comprising insoluble hydrous oxide particles of one or more selected elements, such solutions being exemplified in application Ser. No. 8,022, tiled Feb. 2, 1970, now U.S. Pat. No. 3,657,003. The combined source and colloidal solution are then subjected to a dispersive force to (l) fractionate the metal source to form the plurality of liquid metal particles, and (2) disperse the non-coalescing particles within the colloidal solution. Where the liquid metal source is initially fractionated in a suitable manner, the dispersive force then merely disperses the non-coalescing particles.

BACKGROUND OF THE INVENTION (l) Field of the invention This invention relates to a method of forming and dispersing discrete, non-coalescing liquid metal particles in an yaqueous medium, and more particularly, to a method vof forming and dispersing discrete non-coalescing particles comprising a metal in a liquid state at a temperature below 100 C., including a liquid metal selected from Hg, Ga, alloys of Hg, alloys of Ga and mixtures thereof, and liquid eutectics of other metals.

(2) Discussion of the prior art Liquid metals such as Hg, Ga, eutectics, etc., have wide application in forming alloys with and coatings for other metals or material. For many of these applications, a greater surface area of the liquid metal is desired to either increase the reactivity thereof or insure uniformity with respect to coatings achieved therewith. A means for achieving greater surface area includes impregnating brous brushes or applicators with the liquid metal. However, due to the high surface tension of most liquid metals in poo form, no capillary-rise within the individual fibers occurs. To obviate this, a technique is needed whereby small individual particles of the liquid metal can be formed and applied'to the fibrous material, preferably in a form of a dispersion. Heretofore, however, it has not been possible to (l) disperse liquid metals such as Hg and Ga in a liquid medium and/or (2) maintain a dispersion without immediate coalescence of the dispersed liquid metal particles.

The liquid metals, such as Hg, IGa, are highly reflective and are of use in various reflective and optical systems, such as flys eye mirrors, markers, highway signs, and advertising displays, etc. Such systems are generally discussed and revealed in part, for example, in U.S. Pat. 3,493,286. An inherent problem, however, is the inconvenience of handling small quantities or particles of these liquid metals, eg., Hg. A technique whereby individual, uniform, non-coalescing liquid metal particles can be formed quickly and deposited uniformly in a non-coalescent state is therefore needed.

The manufacture of integrated circuits involves the formation of both active and passive circuit components in a single piece of wafer material which may only be as large as one inch in diameter. Each wafer may have thereon as many as 1,000 identical units, with each unit being formed simultaneously by a microphotographic process using a ilys eye system. This particular system uses a multilens technique and derives its name from the similarity between a ilys eye and the structure of the composite lens used in the system. In the multilens system, a plurality of identical lenses are formed in a plane, the number of lenses corresponding to the number of desired images, so that each lens will produce a reduced identical image of a single object in the same focal plane.

A conventional technique for producing a tiys eye lens mold is revealed in U.S. Pat. 3,526,959 wherein a heated tool is indented in a thermoplastic block and allowed to cool in place. After cooling, the tool is removed leaving a lens replica in the block. The process is similarly repeateduntil a composite array is formed in the block. A metal replica of the lens array is then formed whereafter the thermoplastic material is stripped off. A positive metal mold is formed by depositing a metal over the replica land the replica is then stripped away. Inherent problems with the above conventional technique are (l) time required to mechanically make the array, and (2) limitations with respect to the size of the lens replicas and the spatial tolerances between the individual lenses of the array. Therefore, a technique whereby a plurality of lens replicas can be formed simultaneously and in a desired array is desirable. A method whereby a plurality of metal particles are simultaneously deposited on a surface in the desired array and having the desired lens shape is therefore needed in the fabrication of a flys eye lens mold.

SUMMARY OF THE INVENTION This invention relates to a method of forming and dispersing a plurality of discrete, non-coalescing liquid metal particles in an aqueous medium and more particularly, to a method of forming and dispersing discrete, noncoalescing particles comprising a metal in a liquid state at a temperature below v" C., including a liquid metal selected from Hg, Ga, alloys of Hg, alloys of Ga, mixtures thereof, and eutectics of other metals.

Briefly, the inventive technique involves selecting a source of a liquid metal or metal alloy, i.e., a metal or alloy which is in a liquid state at a particular temperature, typically below 100 C., destined to be employed. The source is combined, at the desired temperature, with a stable aqueous colloidal solution, formed by a hydrolysis and nucleation reaction, comprising insoluble hydrous oxide particles of one or more selected elements, the particles having a size within the range of 10 A. to 10,000 A. The hydrolysis reaction includes dissolution of a salt of the selected element in an aqueous medium and maintenance of the pH of the aqueous medium at a point where no flocculate results. The resultant combination or mixture is then subjected to a dispersive force to (l) break up or fractionate the liquid metal source into a plurality of discrete particles having uniform size and shape, and (2) uniformly disperse the resultant liquid metal particles through the colloidal solution. Where the liquid metal source is initially fractionated in a suitable manner, the dispersive force then merely uniformly disperses the particles. The resultant dispersed discrete liquid metal particles will not coalesce while being dispersed and upon a subsequent settling are non-coalescent for a relatively long period of time.

3 DESCRIPTION OF THE DRAWING.

The present invention will be more readily understood by reference to the following drawing taken in conjunction with the detailed description wherein: 1

FIG. 1 is a cross-sectional view of a discrete source of a liquid metal combined with an aqueous stable colloidal solution contained in a suitable container;

LFIG. 2. is a cross-sectional view of a plurality of liquid metal particles fractionated from the liquid metal source of FIG. 1 and uniformly dispersed throughout the colloidal solution of FIG. l to form a dispersed mixture;

FIG. 3 is a cross-sectional view of the dispersed mixture of FIG. 2 formed within a container, housing a substrate upon which the discrete particles of FIG. 2 are destined to be deposited;

FIG. 4 is a cross-sectional view of the substrate of FIG. 3 upon which is deposited the discrete liquid metal particles of FIG. 3;

FIG. 5 is a cross-sectional view of the liquid metal particles deposited substrate of FIG. 4 which has a covered layer or plate thereon to permanently x the position of the deposited metal particles with respect to one another;

FIG. 6 is a cross-sectional view of the liquid metal particles of FIG. 2, deposited on a suitable base, and covered with a plastic coat;

FIG. 7 is a cross-sectional view of a plastic block formed from the plastic coat of FIG. 6, having metal layers evaporated thereon;

FIG. 8 is a cross-sectional view of the block of FIG. 7 having an electroplated replica plated thereon;

FIG. 9 is a cross-Sectional view of the metal replica of FIG. 8 with the plastic block stripped away;

FIG. 1Y0 is a cross-sectional view of the metal replica of FIG. 9 after a selective etching treatment;

FIG. 11 is a cross-sectional view of the metal replica 0f FIG. 10 having a metal layer evaporated thereon;

FIG. 12 is a cross-sectional view of the replica of FIG. 11 having a positive metal mold plated on the metal layer of FIG. 11; and

FIG. 13 is a cross-sectional View of the positive mold of FIG. 12 after it has been separated from the metal replica of FIG. 12.

DETAILED DESCRIPTION The present invention has been described primarily in terms of forming and dispersing, in a selected aqueous colloidal solution, a plurality of discrete, non-coalescing liquid metal particles comprising mercury or gallium or certain specied liquid eutectics. However, it will be understood that such description is exemplary only and is for purposes of exposition and not for purposes of limitation.

It will be readily appreciated that the inventive concept described is equally applicable to forming and dispersing in the selected aqueous medium or solution a plurality of discrete, non-coalescing liquid metal particles of any metal, including alloys of Hg and Ga and other liquid metal eutectics, which can be maintained in the liquid state at a suitable temperature, i.e., a temperature which does not alfect the stability of the selected aqueous solution; providing, of course, that the selected liquid metal does not react with the aqueous solution selected.

Referring to FIG. 1, at least one discrete suitable metallic source 60 is selected. A suitable metallic source is one comprising a liquid metal, e.g., Hg, Ga, or a metallic alloy, e.g., Ga (62 weight percent)-In (22 weight percent)-Sn (16 weight percent), melting point =10.7 C.; Ga (82 weigh't percent)-Sn (12 weight percent-Zn (6 weight percent), melting point=17 C.; Sn (10.65 weight pcrcent)-Bi (40.63 weight percent)-'Pb (22.11 weight percent)-In (18.1 weight percent)--Cd (8.2 weight percent), melting point=46.5 C.; Bi (44.7 weight percent)-Pb (22.6 weight percent)-Sn (8.3 weight percent)-Cd (21.3 weight percent), melting point=58.2 C.; In (5l weight percent)-Bi (32.5 weight percent)-Sn (16.5 weight percent), melting point=60.5 C.; Bi (50 weight percent)-Pb (25 weight percent)-Sn (12.5 weight percent)-Cd (12.5 weight percent), melting point=70 C.; Bi (50 weight percent)-Pb (26.7 Weight percent)-Sn (13.3 weight percent)-Cd (10.0 weight percent), melting point=70 C.; In (67 weight percent)- Bi (33 weight percent), melting point=70 C.; Bi (51.6 weight percent)-Pb (40.2 weight percent)-Cd (8.2 weight percent), melting point: 91.5 C., which will not 'react with a suitable stable colloidal solution 61 with which it is destined to be combined. By a liquid metal or alloy is meant a metal or alloy in the liquid state at a suitable temperature. A suitable temperature is a temperature at which the colloidal solution 61 remains in a stable condition, and typically is less than C. The discrete liquid metal source 60 is then combined or mixed with the suitable colloidal solution 61, contained in a suitable container 62, to form a mixture. The source 60 can be added in an amount ranging from about 0.5 to about 74% by volume of the resultant mixture. It is, of course, understood that a suitable container 62 is one which will not react with either the source 60 or the solution 61 at the temperatures employed. Some typical suitable containers comprise glass, plastics, etc. It is also to be understood, that although the liquid metal source 60 has been shown in the form of a mound or irregularly shaped body in FIG. 1, this is for illustrative purposes only and the liquid source may comprise a discrete liquid metal layer or a plurality of droplets, particles, etc. (where such a plurality of liquid particles can be formed without coalescence thereof).

A suitable colloidal solution 61 includes at least one aqueous wetting solution revealed in Kenney, Ser. No. 8,022, filed Feb. 2, 1970, now U.S. Pat. No. 3,657,003, entitled Nondetergent, Aqueous Wetting Solutions and Methods of ProducingY Same, assigned to the assignee i hereof and incorporated by reference herein. The wetting solution is generally described as a stable colloidal solution formed by a controlled hydrolysis and nucleation in an aqueous medium wherein the colloidal particles 63 (greatly enlarged for illustrative purposes only) of the colloidal solution 61 (l) have a size within the range of 10 A. to 10,000 A., and (2) are an insoluble hydrous oxide of one or more selected elements. The hydrolysis Ysource 60 and the colloidal wetting solution 61 is then Vsubjected to dispersion by means of a dispersive force created by any conventional dispersive device (not shown). Such devices are well known in the art, some typical ones being conventional stirrers (magnetic, mechanical) and vibrators (sonic, mechanical). Referring to FIGS. 1 and 2, the resultant dispersive force breaks up 'or fractionatcs the liquid metal source 60 into a plurality of discrete liquid metal particles or spheres 64 (enlarged for illustrative purposes only). The discrete metal particles 64 are uniformly dispersed throughout the colloidal wetting solution 61 and will not coalesce, i.e., fuse or unite together, While under the iniluence of the dispersive force. By selecting proper dispersion conditions, including the quantum of the dispersive force, the size of the particles 64 can be maintained uniform. The proper dispersion conditions are well known in the art or can be easily ascertained experimentally by one skilled in the art. It is, of course, understood that the liquid metal source 60 may be combined with solution l61 prior to initiating the dispersive force or after initiating the dispersive force. It is also of course, understood that where the source 60 comprises a plurality of individual particles of a liquid metal, which `can be combined with solution 61 without coalescence thereof, the resultant dispersive force can either fractionate these individual particles or just disperse the individual particles in solution 61 Without further fractionation thereof.

`The particles 64 are typically more dense than the colloidal wetting solution 61 and so settle out (migrate tothe bottom of the solution) from the solution 61 after several minutes, typically 2 to 60 minutes, once the dispersive force ceases to exist. However, even upon settling out or separating, the discrete liquid metal particles 64, e.g., Hg, Ga, are non-coalescent, i.e., do not agglomerate. This non-coalescent state is of fairly long duration, typically in the order of from several days to several months.

When a uniform layer of a liquid metal, having a large surface area, is desired to be deposited on a surface, for (1) reaction therewith, (2) the covering thereof or (3) the fabrication of a reflective and/or an optical system, eg., a iiys eye mirror, the dispersed liquid metal particles are allowed to settle out on that surface. Referring toFIG. 3, a suitable substrate 66 is placed into the container 62 prior to the addition of the solution `61 and the liquid metal source 60. A suitable substrate 66 may omprise any material, including, for example, metals such as gold 'and copper, glass, plastics, etc., which is desired to be (l) reacted with the liquid metal particles 64, or (2) covered by the liquid metal particles 64.

`:Where a fiys eye mirror is contemplated, glass is a preferred substrate.

The colloidal solution 61 is added to the container 62 housing the substrate `66. A dispersive force is created `within solution 61, by conventional means, as previously discussed, 'and the metallic source 60 is then added to form the dispersed mixture comprising the discrete, noncoalescing liquid metal particles 64 uniformly dispersed throughout the solution `61. Referring to FIG. 4, the dispersed, non-coalescing liquid metal particles 64, eg., Hg, Ga are allowed to settle on a surface 67 of the substrate 66 to deposit a uniform layer or carpet `68 of discrete liquid metal particles `64 which are non-coalescent. In this regard, it is to be noted that, as illustrated in FIG. 4,

"the particles remain non-coalescent even when there is circumferential contact of the individual particles to one another, typically as evidenced by microscopic examination at a magnification of 800x. It is also to be noted that the layer 68 can be made relatively uniform with respect to the size, shape and spacing between the parv-ticles 64 by proper control of the dispersion conditions as previously mentioned. The `carpet or layer '68 may either remain as a coating layer or react with surface 67 of the substrate 66, depending of course upon the substrate material selected and the liquid metal particles deposited. As previously mentioned, the non-coalescent state maybe retained for a relatively long period of ltime vwhich can range `from several hours or days to several months. y

Where the carpet or layer 68 is desired .to be permanently fixed, i.e., fixed with respect to the spatial relationship of the particles to one another on a substrate 66, such as glass or unreactive. plastic, the solution 61 may rfirst be removed from the container 62 by any conventional means known in the art, e.g., pumping means. It is to be noted that alternatively, where, as in the case of gallium, for example, the liquid metal solidifies at a 'temperature abovey the freezing temperature of the colfrozen, i.e., are solidified. Referring to FIG. 5, a suitable cover layer of plate 69 is then provided to cover the layer -68 and permanently fix the frozen particles 64. l

The cover layer or plate 69 may be fabricated first and then placed over layer 68. In this regard, the cover plate 69 may be fabricated from any material in such a manner as to have indentations corresponding to the shape and location of each discrete frozen particles 64. Where a flys eye mirror, or other optical system is contemplated, the plate 69 may comprise a refractive, optical medium such as glass, fully cured and clear plastics, etc. A conventional sealing means (not shown), e.g., a gasket seal, sealing the cover plate 69 to the substrate i6'6 is then provided. Alternatively, the cover layer or plate 69 may be formed in situ by coating the carpet 68y with any of a number of conventional photosensitive polymeric materials, which are well known in the art, to first form a liquid or semi-liquid layer which contours and conforms to the individual frozen particles 24 in their spatial relationship to one another. The liquid or semi-liquid polymeric layer is then photographically exposed to a full cure whereby the solid cover plate 69 is formed. In place of photosensitive polymeric materials, it is, of course, to be noted that a plastic, eg., acrylics, which can be cast, utilizing techniques will known in the art, may be ernployed.

In an alternative embodiment of the present invention, a ys eye mold may be prepared using a conventional plastic casting method. Referring back to FIG. 2, as discussed previously, non-coalescing liquid metal particles 64, e.g., Hg, Ga, alloys, etc., are dispersed in the selected colloidal wetting solution 61. The particles '64 are formed having a desired size and shape. As discussed previously, the size and shape of the particles 64 and the spatial relationship therebetween can be controlled by selecting proper dispersion conditions, i.e., conditions which are well known in the art to one skilled therein or are easily ascertainable experimentally.

Referring to FIG. 6, as discussed previously, the dispersed, non-coalescing liquid metal particles 64 (FIG. 2) are allowed to settle on a flat surface 71 of a suitable base 72 to deposit a layer 73 comprising the non-coalescent discrete metal particles 64. A suitable base 72 may cornprise any material which is unreactive with either the colloid solution 61 (FIG. 2) or the liquid metal particles 64. Preferably, the base 72 should comprise a parting material such as polytetraiiuoroethylene. However, it is, of course, understood that alternatively, a base 72 cornprising a nonparting material may be employed whereby any conventional mold release agent or material, e.g., silicone, well known in the art, can be coated on the surface 71 thereof prior to the settling thereon of the particles '64.

Each resultant deposited particle` 64 of the layer 73 has a surface 70, not in contact with the base 72, which corresponds to the shape of a desired lens destined to be ultimately formed or fabricated in the flys eye mold. The deposited particles y64 of the layer 73 also corresponds to a desired array of the lens shapes or replicas destined to be formed in the flys eye mold. Again, it is to` be noted that the desired shapes and array can be controlled by the dispersion conditions as well as the settling conditions employed.

As discussed previously, the colloid solution 61 is removed and the layer 73 is solidified by lowering the ternperature thereof, typically for the case of liquid gallium (M.P.'=30' C.) to a temperature :below 25 C. Again, it is to be noted that where, as in the case of Ga, the liquid metal `solidiiies at a temperature above the freezing temperature of the colloid solution 61 (FIG. 2), the par- Vticlesmay be frozen first and the colloid solution 61 may then be removed by any suitable means,e.g., pumping, decanting thereof, etc.

i Referring again to FIG. 6, the solidified or frozen layer 73 and surface 71 of the base 72 are covered by a plastic casting composition comprising a castable plastic such as, e.g., methyl methacrylate, in a carrier medium such as ethyl ether, acetone, etc. The castable plastic is cast over layer 73 and surface 71, and solidied by evaporating the carrier medium, utilizing conventional materials and procedures well known in the art to one skilled therein, to form a plastic coat 74 having a surface 76 conforming (1) to the shape of the surface 70 of the particles '64 of layer 73, and (2) to the spatial array of the discrete, solidified metal particles 64. The temperature of the base 72, the layer 73 and the plastic coat 74 is raised to a point, e.g., above 25 C. for gallium, whereby the particles `64 return to the liquid state, Le., melt. The plastic coat 74 is then removed from the base 72 to yield a plastic block 75 having a desired array of lens replicas 78 in the surface 76 as illustrated in FIG. 7.

The block 75 is placed in an evaporating apparatus (not shown) where a thin layer of chrome 77 is deposited over surface 76 of block 7S, thereby conforming to the replicas 78. Subsequently, a thin layer of copper 79 is deposited over the chrome layer 77. It has been found that chrome will adhere to the plastic surface 76, but copper does not plate easily on a pure chrome surface. It is only necessary, however, that the copper layer 79 remain in place long enough to allow initial copper plating to take place in a subsequent plating step.

Referring to FIGS. 7 and 8, the copper layer 79 is built up, typically to a thickness of from P/s to 1/2, Vusing standard electroplating techniques well known in the art, to form a rigid metal replica 81 of the lens replica array on surface 76 of the plastic block 75. Copper is chosen to form the metal replica `81 because of its low stress characteristics and inherent hardness. Alternatively aluminum can be used; however, due to its higher hardness, copper is preferred.

As illustrated in FIGS. 8 and 9, the plastic block 75 is removed or stripped from the metal layer 77 :by suitable conventional means including machining and chemical solvent treatment. The chrome layer 77 is then removed, as shown in FIG. 10, from the copper replica, by a selective etching process, using materials and techniques well known in the art, whereby a smooth, clean copper surface is obtained.

Referring to FIG. 11, the copper replica 81 which is the negative of the ys eye mold to be ultimately formed, is cleaned using any suitable cleaning agent and then replaced in a vacuum apparatus where an interlaced chrome-copper release agent layer 82 is plated by a conventional evaporation process on the replica 81 according to rigid dimension specications corresponding to the desired array. Following the deposition of the thin layer 82 of chrome-copper release agent, the replica 81 is removed from the evaporating apparatus and subjected to la copper electroplating bath to build up a copper backing.

The copper backing typically has a thickness of Eye to 1/2" whereby a rigid positive mold 83, illustrated in FIG. 12, is formed which will Ibe destined for use in a mold press.

Referring to FIGS. 12 and 13, after electroplating't'he desired thickness, the copper replica 81 is stripped from the mold 83 by administering a mechanical shock force by means, not shown, to the positive mold 83 so that the copper replica 81 is separated from the positive mold 83 at the rst chrome interface 82(a) of layer 82, leaving the positive, chrome-surfaced copper mold 83. The chrome surface 82(a) provides a chemically stable, scratch-resistant surface 'which will not oxidize with age when heated. The mold 83 is then machined to size and used as a conventional mold in a press to form the desired lenses.

positive mold. In this manner, all the prior electroplatin'g steps of the preferred method are eliminated.'

EXAMPLE I A colloidal wetting solution was prepared in a suitable container by dissolving one weight percent SnCl2.5H2O in ml. of deionized water. Two weight'percent of SnCl2.2H2O was then dissolved in the resultant solution. Finally, 1.5 weight percent SnCl2.2H2O was added and dissolved therein to form a yellow colloidal wetting *solution. Ten weight percent liquid mercury was added to the wetting solution to form a mixture. Theresultant mixture was stirred at room temperature with a magnetic stirrer at about 100 r.p.m. forten minutes. A plurality of discreate spherical, non-colaescing mercury particles or droplets of uniform size and shape formed and were uniformly dispersed throughout the colloidal solution. After 20 minutes, the discrete particles had settled to the bottom of the container. Microscopic examination yof the settled particles at magnification of 800x revealed that coalescence did not occur although there was apparent circumferential contact between the individual particles. Also, on the settled discrete, non-coalescent droplets, mirror images of the surroundings were evident.

EXAMPLE II The procedure of Example =I was repeated except that liquid gallium was employed at atemperature of 25 C. (Ga tends to subcool without freezing; if F.P. is 'about 30 C.). The results of-Example I were observed.

EXAMPLE III The procedure of Example I was repeated except that the colloidal solution was an iron wetting solution. One hundred ml. of deionized water was first heated to 70 C. One weight percent FeCl3.6H2O was dissolved therein. The final pH of this solution was 1.5-2.0. The results of Example I were obtained.

EXAMPLE 1v The procedure of Example II was repeated except the wetting solution was that of` Example III. The results of Example II were obtained. p p v EXAMPLE v One weight percent of CuCl2.6H2Owasgdissolved in deionized' water. The pH `of the resultant solution 4was raised to 7.2 by adding 0.1 N NH4OH. The resultant colloid wetting solution was heated toa temperature of 50 C. whereupon l0 volume'percentV of an alloy comprising 44.7 weight percent of Bi; 22.6 weight percent of Pb; 8.3 weight percent of Sn; 5.3 weight percent of Cd and 19.1 weight percent of In was added thereto. The combined aqueous solution and metal'alloy (liquid at V50" C.) were mechanically stirred at a rate in excess of 100 r.p.m. A non-coalescing emulsion of the liquid alloy dispersed in the colloid solution formed.

EXAMPLE VI One weight percent of AlCl3.6H2O was dissolved `in deionized water. The pH of the resultant solution `was raised to 6.0 by adding 1.0 N NaOH. The solution was then heated to 70 C. and 2 volume percent of an alloy, comprising 51 weight percent In, 32.5 weight percentBi and 16.5 weight percent Sn, was added to the resultant colloid wetting solution. The alloy was in a liquid state at 70 C. The combined aqueous solution and lliquid metal alloy was stirred at a rate in excess of 100 r.p.m. ,and dispersion of discrete, non-,coalescing particles of theliquid alloy inthe aqueous solution resulted. .The particles were allowed to settle for one minute and a portion of the re.- sultant dispersion was poured onto a at glass plate and allowed to cool. A solid layer of sessile drops on the; glass plate resulted. The drops were from 3 Vto 5 mil in diameter.

9 EXAMPLE Vu 0.5 weight percent of NiCl2.6H2O was dissolved in deionized water. The pH of the resultant solution was raised to 7.9 by adding 0.1 N NHOH. To the resultant colloidal wetting solution was added 0.5 volume percent of a liquid alloy comprising 62 weight percent Ga, 22 weight percent In and 16 weight percent Sn. The combined aqueous solution and liquid metal alloy were mechanically stirred whereby a non-coalescing emulsion of the liquid alloy dispersed in the colloidal solution formed.

EXAMPLE VIII 0.5 weight perecnt of LaCl3.6H2O was dissolved in deionized water. To the resultant colloidal wetting solution was added one volume percent of a liquid alloy comprising 82 weight percent Ga, 12 weight percent Sn and 6 weight percent Zn. The combined aqueous solution and liquid metal alloy were mechanically stirred whereby a non-coalescing emulsion of the liquid alloy dispersed in the colloidal solution formed.

EXAMPLE IX 0.5 weight percent CrCl3.6H2O was dissolved in deionized water. The pH of the resultant solution was raised to 5.4 by adding 1 N NaOH. The resultant colloidal wetting solution was heated to 75 C. and 5 volume percent of an alloy comprising 50 weight percent Bi, 25 weight percent Pb, 12.5 weight percent Sn and 12.5 weight percent Cd (liquid at 75 C.) was added thereto. The combined aqueous solution and metal alloy (liquid at 75 C.) was mechanically stirred whereby a dispersion of discrete, non-coalescing drops of the liquid alloy in the aqueous colloidal solution resulted. The solution was cooled to a temperature below 70 C. and the non-coalescing par ticles were frozen. The frozen liquid alloy drops had a size of l to 2 mils in diameter.

It is to be understood that the above-described embodiments are simply illustrative of the principles of the invention. Various modications and changes may be devised by those skilled in the art which embody the principles of the invention and fall within the spirit and scope thereof.

What is claimed is:

1. A method of forming a stable aqueous dispersion comprising a plurality of dispersed liquid metal particles, which comprises dispersing an amount ranging from 0.5 to 74 percent by volume of the plurality of liquid metal particles in a stable aqueous colloidal solution, formed by a hydrolysis and nucleation reaction, comprising insoluble hydrous oxide particles of one or more selected elements, said particles having a size within the range of A. to 10,000 A. and said hydrolysis reaction including at least 10 (l) dissolution of a salt of said selected elements in an aqueous medium, and (2) maintenance of the pH of said aqueous medium at a point where no tlocculate results.

2. The method as dened in clairn 1, wherein said one or more elements is selected from the group consisting of Be, Mg, Ti, Zr, V, Cr, Mo, W, Mn, Fe, Co, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Hg, Al, In, Tl, Si, Ge, Sn, Pb, Bi, La, Ce, Th, U and mixtures thereof.

3. A method of forming and dispersing a plurality of discrete, non-coalescing liquid metal particles, in an aqueous medium, which comprises:

(a) combining an amount, ranging from 0.5 to 74 weight percent by volume, of a discrete source of the liquid metal with a stable aqueous colloidal solution, formed by a hydrolysis and nucleation reaction, comprising insoluble hydrous oxide particles of one or more selected elements, said particles having a size within the range of 10 A. to 10,000 A. and said hydrolysis reaction including at least (l) dissolution of a salt of said selected element in an aqueous medium, and (2) maintenance of the pH of said aqueous medium at a point Where no occulate results; and

(b) subjecting said combined discrete metal source to a dispersive force to (1) fractionate said discrete source to form the plurality of discrete, non-coalescing metal particles, and (2) disperse the plurality of discrete, non-coalescing particles within said colloidal solution.

4. The method as dened in claim 3, wherein: said one or more elements is selected from the group consisting of Be, Mg, Ti, Zr, V, Cr, Mo, W, Mn, Fe, Co, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Hg, Al, In, Tl, Si, Ge, Sn, Pb, Bi, La, Ce, Th, U and mixtures thereof.

5. The method as defined in claim 3, wherein: said discrete liquid metal source comprises a composition having at least one metal selected from the group consisting of Hg, Ga, Bi, Pb, Sn, Cd, In and Zn.

References Cited UNITED STATES PATENTS 1,491,250 4/1924 Von Hoessle 252-313 R 3,657,003 4/1972 Kenney 252-313 R X 2,686,159 8/1954 Webb et al. 252-313 R 3,532,518 10/1970 DOttavio 252-313 R X RICHARD D. LOVERING, Primary Examiner U.S. Cl. X.R.

temmen Smm Mifemmoemne @RPWMQ @@RRE PmemNe. TEJH waged Sentemoec` ll lQf??` ummm-(e J.' T. Kenney?. A. Limi t is certified hat error appears in the above-idemified patent and thm sadLeuel-s Pmem are hereby corrected as shown beow:

ln the specification, column l, line 50, "mateial" should Teed -rr1e.L;e`1CieLls-d Column 2, line 20, "3,526,959'? fshould reed 3,526,9MQ, Column 3, line 50, Hliquid euteeties" should reed "liquid metal euteCtiCs--g line 68, (12 weight %-Zn should read (12 weight %)Zn. Column LL, line M2, "6l should Vfeed --6l, Column 6, line 25, 1"will known" should ead Well Known-H` Column 7, line LL, nCnome interface should Tead -m-cnome copper interface-- Column 8, lines lll-l5, "dis-Create" should :read --disciete--g line l5, ."coleiescingH Should feed --coalescing---, line 29, "if lp." should read--its Zp-f.

ln the Claims, claim LL, Column lO, line 30,Y "sei-d" Should begin a new paragapn; line 35, claim 5, o "Saidf should begin e. new paegrepn.

Signed and sealed this 18th day of December 1973,.

` (SEAL) Attest:

EDWARD In FLETGEER, Je, RENE 1) TEGTMEYER .Attesting ficea Acting Commissioner of* Patents e zj; Sim Amwiomo 1 f if ff M111 Pmem wu, 2,758All1 umd Sentember 11. 1cm

www@ Jy T. Kenneyuf, A. Litt it is certified hat errof appears in :he above-identified patent and that saidLetters Pmem are hereby corrected as shown beiow:

ln J@ne specification, column l, line 5C, "material should Tend "materials" Column 2, line 20, "3,526,959

should fea@ "3,526,919--- Column 3, 11n@ 5o, "liquid euteotios" should feed "liquid metal eutectiCs--g line 68,

(12 weight %-Zn Should read (12 weight %)Zn. column L1,

line M2, "6lH should read --6l,. Column 6, line 25, Hwill knownH should Tead --well known; Column 7,' line LL,

Cnfome interface" Should read --cnome oolopeir interface-- Column 8, lines lll-l5, dis-oeate" should read --discfete--g line l5, "colenescingH should feed --coalescing--g line 29,

ln the Claims, claim LL, Column lO, line 3C,- "said" should begin a new pafagapn; line 35, claim 5, "`said should begin a new paagiapn.

Signed -and sealed this 18th day o December 1973.`

(SEAL) Attest; l

EDWARD M., FLETCHER, JR, RENE D., I'EG'ITIVLEYER Attesting Officer Acting Commissioner of Patents 'i i, I 

